While not an expert on this subject, I think my input might help a light go on for somebody reading this. You seem to have a mismatch in your configuration somewhere. Cookies from "emmasbridaljewelry.com" and "www.emmasbridaljewelry.com" are not interchangeable.
You have your domain set up to always add "www". If I go to http://emmasbridaljewelry.com, my browser settings show a session cookie with the correct value, but there are some differences. The site is listed as "emmasbridaljewelry.com" but the HOST value for the cookie is "www.emmasbridaljewelry.com"
That causes your site to throw the following error:
If I clear my cookies and then browse to http://www.emmasbridaljewelry.com/, the new browser cookie shows www.emmasbridaljewelry.com for both site and HOST. The error then goes away, and everything seems fine. As soon as I click a link, the session blows up and I get the same error message. When I check my cookies again, I see the site has been reset to emmasbridaljewelry.com, and no longer matches the HOST.
What happens if you configure your domain to always remove "www" in the DH panel?